One of the shortest chapters in the Quran,
“The Oneness of Allah,”
summarizes the nature of God in five verses,
“In the name of Allah, the Infinitely Compassionate, the Most Merciful: Say, ‘He is Allah, the One; Allah, the Eternal Originator; He does not bear children, nor was He born; and He is beyond compare.’”
The most fundamental Islamic teachings about God are contained in the previous verses; there is only one God, He is eternal, unique, and has no kinship, creator, or resemblance to any human being.
Throughout their mission, every prophet stated some of the divine attributes of God. Prophet Abraham said,
“My Lord is He who gives life and causes death.” (2:258)
When confronting Pharaoh, Moses said,
“Our Lord is He Who gave each thing its form and nature then guided it aright” (20:50).
These two verses describe God and His relation to human beings; however, God’s being extends far beyond His relation to mankind. Imam Ali described God in the following manner: “He who assigns to Him different conditions does not believe in His oneness, nor does he who likens Him, grasp His reality. He who illustrates Him, does not signify Him; he who points at Him and imagines Him, does not mean Him. Everything that is known through itself has been created, and everything that exists by virtue of other things is the effect of a cause. He works but not with the help of instruments; He fixes measures, but not with the activities of thinking; He is rich, but not by acquisition. Time does not keep company with Him, and implements do not help Him. His being precedes time, His existence precedes nonexistence, and His eternity precedes beginning. By His creating the senses, it is known that He does not possess such senses. By the contraries in various matters, it is known that He has no contrary, and by the similarity between things it is known that there is nothing similar to Him. He has made light the contrary of darkness, brightness that of gloom, dryness that of moisture, and heat that of cold. He produces affection among inimical things. He is not confined by limits, nor counted by numbers. Material parts can surround things of their own kind, and organs can point out things similar to themselves…Through them, the Creator manifests Himself to the intelligence, and through them He is guarded from the sight of the eyes…He has not begotten anyone lest He be regarded as having been born. He has not been begotten; otherwise, He would be contained within limits. He is too high to have sons…Understanding cannot think of Him so as to give Him shape…”
God expresses His own eternity and perpetuity in the Quran when He states,
“Everything on earth shall perish, but the face of Allah will remain, full of majesty and honor.” (55:26-27)
 Al-Tawhid, c.112.
 Nahj al-Balagha (The Peak of Eloquence), sermon #186.